Completing her minimal look with a simple bracelet and cream clutch bag, Charlene added a dash of colour with a vibrant purple lipstick.
Albert wore a smart black dinner suit as he walked the red carpet with his statuesque wife.
Earlier in the day, Monaco's sovereign and his glamorous consort headed to the Grand Prix itself. In a break from tradition, Charlene took to the driver's seat instead of Albert to drive the ceremonial lap of honour that begins the day's proceedings.
Dressed in a bright coral dress, nude sandals and large sunglasses Charlene, 35, got behind the wheel of the luxury sports car, with Albert in the passenger seat.
Members of the Grimaldi family joined Albert and Charlene at the Monte Carlo track. New parents Andrea Casiraghi and Tatiana Santo Domingo strolled together in the sunlight and Andrea's brother Pierre also attended with his girlfriend Beatrice Borromeo.
Beatrice chose a summery floral dress and sunglasses with circular frames as she walked hand-in-hand with a smartly-dressed Pierre.
Fresh from his trip to neighbouring Cannes for the film festival, Michael Douglas joined the racegoers.
Princess Charlene has been busy with engagements of late. The Monegasque royal enjoyed some of the glitz and glamour of Cannes on Wednesday evening as she attended Roberto Cavalli's exclusive boat party.
The beautiful blonde Princess looked sleek in an all-black Roberto Cavalli outfit, adding a pop of colour with a bright green clutch bag. The absence of her husband Albert didn't hold her back – Charlene partied the night away, laughing and mingling with the A-list crowd on Roberto's luxury yacht.